Thermal relief for specified components | 🧨 KiCad Rules

Intro

This series of short notes showing practical examples of using custom text-based rules for KiCad EDA.

🔺 Issue Description

I have many 0402/0603 LEDs on the board (mostly for power and signal statuses):

Since ground zone have default solid connection I want apply thermal relief only for LEDs, because they more sensitive to heat and to prevent uneven heating of the pads:

🔧 Issue Fix

Board -> Custom Rules -> DRC Rules:

(rule led_thermal_relief
    (constraint zone_connection thermal_reliefs)
    (condition "A.Reference=='LD*'")
    (constraint thermal_relief_gap (min 0.2mm))
    (constraint thermal_spoke_width (min 0.2mm))
)

Note 1: if you use another reference designator change LD to your (e.g. LED, D)

Note 2: you can also use as a condition specific footprint:

(condition «A.memberOfFootprint('LED_SMD:LED_0402_E_1005Metric')»)

✔ Fixed

🔴 BEFORE	🟢 AFTER

🌟 Related Article

How to write custom KiCad rule exception? Simple example of courtyard overlap resolve

Conclusions

🟡	Use thermal relief for the most soldering sensitive components
🟢	Using rule it's good development approach instead of any manual pad properties changes
🟢	This tiny rule can save a lot of time and give more repeatable results

kicad rule custom rule

04.12.2025

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